Magnetoresistance effect device, and magnetoresistance effect magnetic head

ABSTRACT

A magneto-resistive effect element body  11  and a hard magnetic layer  12  for applying a bias magnetic field are disposed between opposing first and second magnetic shields  21  and  22 , each made of a soft magnetic material. This magneto-resistive effect element body  11  is comprised of a lamination layer structure portion in which there are laminated at least a free layer the magnetization of which is rotated in response to an external magnetic field, a fixed layer, an antiferromagnetic layer for fixing the magnetization of the fixed layer and a spacer layer interposed between the free layer and the fixed layer. Then, the magneto-resistive effect element has a CPP type configuration in which a sense current flows to the magneto-resistive effect element body in the direction intersecting the film plane of the lamination layer film. Further, a detection magnetic field is introduced in the direction extending along the film plane direction of the lamination layer film and a bias magnetic field is applied in substantially the direction intersecting the direction in which the above-mentioned detection magnetic field is introduced and in the direction extending along the film plane. In this configuration, under the condition that the detection magnetic field is not applied to the magneto-resistive effect element, magnetic fields substantially applied to the front end and the rear end of the side in which the detection magnetic field is introduced, to be concrete, magnetic fields determined mainly by an induced magnetic field HI induced by the above-mentioned sense current and a bias magnetic field HB are set to the same directions, particularly, in the free layer, whereby a single magnetic domain is nucleated in the free layer with high stability.

TECHNICAL FIELD

The present invention relates to a magneto-resistive effect element anda magnetic head using magneto-resistive head in which an output can bestabilized while a sensitivity can be avoided from being deteriorated.

BACKGROUND OF THE INVENTION

A magnetic sensor or a magnetic head using a spin-valve typemagneto-resistive effect (hereinafter referred to as an “SV type GMR”)element or a tunnel type magneto-resistive effect (hereinafter referredto as a “TN type MR”) element is able to detect a change of an externalmagnetic field based upon a magnetic resistance change generated by achange of a relative angle between a free layer and a fixed layer whosemagnetization is fixed by an antiferromagnetic layer when themagnetization of the free layer made of a soft magnetic material isrotated in response to the external magnetic field.

In this case, in order to detect the external magnetic field at a highefficiency, by a method such as film deposition, annealing in themagnetic field, a uniaxial magnetic anisotropy is given to the freelayer in the direction perpendicular to the direction in which anexternal magnetic field is introduced. As a consequence, although themagnetization of the free layer tends to orient in the two directionsextending along this magnetic anisotropy (the forward direction or thereverse direction relative to the magnetic field to which the anisotropyis given), which direction of the above two directions the magnetizationof the free layer is oriented without application of the externalmagnetic field is not prescribed. As a result, the above-mentionedmagnetic sensor and the above-mentioned magnetic head cannot detect thechange of the external magnetic field with an excellent reproducibility.

On the other hand, at the end portion of the free layer in the directionperpendicular to the aforementioned magnetic anisotropy direction(hereinafter referred to as a “side end portion”), the magnetizationbecomes difficult to orient in the magnetic anisotropy direction due toan antimagnetic field so that a magnetic domain occurs, which causes aso-called Barkhausen noise which causes the rotation of themagnetization to become discontinuous when the magnetization is rotatedin response to the external magnetic field.

Accordingly, when the bias magnetic field is applied to the free layerin one direction of the above-mentioned magnetic anisotropy direction inan opposing relation to the side end portion of the free layer, underthe condition that other magnetic field is not applied to the freelayer, the free layer is nucleated as a single magnetic domain byconfining its magnetization direction in a constant direction. As aresult, the occurrence of the magnetic domain in the above-mentionedfree end of the free layer can be avoided, the Barkhausen noise can beavoided, and the resistance change of the magneto-resistive effectelement can be reproduced by the detection magnetic field with anexcellent reproducibility and at an excellent stability.

Although this bias magnetic field needs a magnetic field intensity highenough to nucleate the free layer as the signal magnetic domain, whenthe intensity of the bias magnetic field is too high, a rotation angleat which the magnetization of the free layer is rotated in response tothe external magnetic field becomes too small so that the sensitivity ofthe magneto-resistive effect element is lowered unavoidably. Therefore,the material and film thickness of the hard magnetic layer are selectedin such a manner that the sensitivity of the magneto-resistive effectelement becomes appropriate.

When the magneto-resistive effect element has a so-called CPP (CurrentPerpendicular to Plane) configuration in which a sense current flows inthe direction perpendicular to the film plane of a magneto-resistiveeffect element body, i.e., in the direction perpendicular to the filmplane of the free layer 1 as shown in FIG. 12, a current magnetic fieldHI generated in the free layer by this sense current Is is generated soas to circulate along the film plane.

At that time, at the respective central portions of a front end 1F ofthe free layer 1 and a rear end 1R on the opposite side of the frontend, which is the side into which a detection magnetic field isintroduced, the current magnetic fields become parallel to the directionin which the bias magnetic field HB is applied and also become oppositeto each other.

Accordingly, as mentioned before, when the bias magnetic field HB isapplied to the free layer of the magneto-resistive effect element MR,the current magnetic field HI acts in the direction in which the biasmagnetic field HB is increased in intensity and also acts in thedirection in which the bias magnetic field is decreased in intensity atany one of the center of the front end of the free layer and the centerof the rear end of the free layer.

Therefore, in order to nucleate the free layer as the single magneticdomain, a bias magnetic field having an intensity high enough to preventthe bias magnetic fields from being canceled out should be applied tothe portion in which the current magnetic field HI acts in the directionin which the intensity of the bias magnetic field is decreased.

However, this bias magnetic field becomes too high in intensity at theportion in which the current magnetic field acts in the direction inwhich the intensity of the bias magnetic field is increased, so that asensitivity at this portion is lowered, accordingly, the output of themagneto-resistive effect element is decreased.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a magneto-resistiveeffect element which can generate a stable output while making itpossible to avoid a sensitivity from being lowered due to a currentmagnetic field caused by a sense current as described above and is alsoto provide a magnetic head using magneto-resistive head using thismagneto-resistive effect element as a magnetic sensing portion.

According to the present invention, the direction of a sense currentflowing to the direction intersecting, e.g., perpendicular to a filmplane of a magneto-resistive effect element to which a bias magneticfield is applied is restricted to a specific direction, whereby asensitivity partly lowered due to unequal current magnetic fields beingcanceled out by a bias magnetic field can be decreased. That is, therecan be constructed a magneto-resistive effect element and a magnetichead using magneto-resistive head which are able to generate high outputwith high stability.

In a magneto-resistive effect element according to the presentinvention, a magneto-resistive effect element body and a hard magneticlayer for applying a bias magnetic field to the magneto-resistive effectelement body are disposed between opposing first and second magneticshields, each of which is made of a soft magnetic material.

The magneto-resistive effect body is comprised of a lamination layerstructure portion in which there are laminated at least a free layer themagnetization of which is rotated in response to an external magneticfield, a fixed layer, an antiferromagnetic layer for fixing themagnetization of this fixed layer and a spacer layer interposed betweenthe free layer and the fixed layer.

Then, the magneto-resistive effect element has a CPP type configurationin which a sense current flows to the magneto-resistive effect elementbody in the direction crossing the film plane of its lamination layerfilm. Moreover, a detection magnetic field is introduced in thedirection extending along the film plane direction of the laminationlayer film, and a bias magnetic field is applied to substantially thedirection which intersects the direction in which the above-mentioneddetection magnetic field is introduced and in the direction extendingalong the film plane of the lamination layer film.

According to the present invention, in this configuration, particularlyin the free layer, under the condition that the detection magnetic fieldis not applied to the magneto-resistive effect element, magnetic fieldssubstantially applied to this free layer at the front end and the rearend of the side into which this detection magnetic field is introduced,to be concrete, magnetic fields determined mainly by an induced magneticfield (hereinafter referred to as a “current magnetic field HI”)generated by the above-mentioned sense current and a bias magnetic fieldHB are set to the same direction.

Further, in the magnetic head using magneto-resistive head according tothe present invention, its magnetic sensing portion is comprised of theabove-mentioned magneto-resistive effect element according to thepresent invention.

As described above, according to the present invention, the magnetichead using magneto-resistive head has the magnetic shield typeconfiguration in which the magneto-resistive effect element is disposedbetween the first and second magnetic shields and has also the CPP typeconfiguration. Under the condition that the detection magnetic field isnot applied to the magneto-resistive effect element, directions HF andHR of magnetic fields applied to this free layer are set to the samedirection at the front end and the rear end of the free layer, in actualpractice, at the central portions of the front end and the rear end,whereby an occurrence of a magnetic domain can be avoided insubstantially the whole region of the side end portion of the freelayer. As a result, there can be constructed the magneto-resistiveeffect element and the magnetic head using magneto-resistive head inwhich a Barkhausen noise can effectively be improved, accordingly, themagneto-resistive effect element and the magnetic head usingmagneto-resistive head which are stable and excellent inreproducibility.

Then, in this configuration in which |HF|>|HR| is fundamentallysatisfied, i.e., in the configuration in which a magnetic field in thedirection perpendicular to the detection magnetic field is increased inintensity in the front portion in which an amount of detection magneticflux is large, the magneto-resistive effect element and the magnetichead using magneto-resistive head can be made stable. On the contrary,in the configuration in which |HF|<|HR| is satisfied, themagneto-resistive effect element and the magnetic head usingmagneto-resistive head can be increased in sensitivity.

However, as will be described later on, for example, with the structuresin which the magneto-resistive effect element and the magnetic headusing magneto-resistive head include magnetic flux guides, under thecondition in which the magnetic fields HF and HR are selected so as toorient in the same direction, the setting of a relationship between themagnetic fields HF and HR and a relationship between the sensitivity andthe stability can be selected arbitrarily.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic perspective view showing a magneto-resistiveeffect element and a magnetic head according to an embodiment of thepresent invention.

FIG. 2 is a schematic perspective view showing a magneto-resistiveeffect element and a magnetic head according to another embodiment ofthe present invention.

FIG. 3 is a schematic cross-sectional view showing a magneto-resistiveeffect element body according to an embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view showing a magneto-resistiveeffect element body according to another embodiment of the presentinvention.

FIG. 5 is a schematic cross-sectional view showing a magneto-resistiveeffect element and a magnetic head according to an embodiment of thepresent invention.

FIG. 6 is a schematic cross-sectional view showing a magneto-resistiveeffect element and a magnetic head according to another embodiment ofthe present invention.

FIG. 7 is a diagram to which reference will be made in explaining thepresent invention and which shows an induced current induced by a sensecurrent flowing through a free layer.

FIG. 8 is a diagram to which reference will be made in explaining thepresent invention and which shows a coordinate system.

FIGS. 9A and 9B graphically illustrate how a magnetic field component,Hx, may be calculated in accordance with the present invention, FIG. 9Cgraphically illustrates how the attenuation degree of a magnetic fieldmay be calculated in accordance with the present invention.

FIG. 10 is a diagram showing distributions of magnetic fields generatedin the depth direction of the magneto-resistive effect element.

FIG. 11 is a schematic perspective view showing an example of arecording and reproducing magnetic head using a magnetic head accordingto the present invention.

FIG. 12 is a diagram showing a sense current and a current magneticfield.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

A magneto-resistive effect (MR) element according to the presentinvention and an MR type magnetic head using this inventivemagneto-resistive effect element will be described.

FIGS. 1 and 2 show schematic perspectives of an MR element 10 and an MRtype magnetic head 100 using this inventive magneto-resistive elementaccording to the present invention, respectively.

The MR element 10 includes an MR element body 11 and a hard magneticlayer 12 for applying a bias magnetic field to this magneto-resistiveeffect element body disposed between first and second magnetic shieldsopposing to each other, e.g., first and second electrode and magneticshields 21 and 22 serving as electrodes as well and each of which ismade of a soft magnetic material having a conductivity.

The example shown in FIG. 1 shows the case in which the MR element body11 is disposed in a facing relation to a surface into which a detectionmagnetic field is introduced, i.e., a forward surface 13. FIG. 2 showsthe case in which the MR element body 11 is disposed at a positionretreated from this forward surface 13 in the depth direction such thata detection magnetic field introduced from this forward surface 13,i.e., in a magnetic head, a signal magnetic field from a recordingportion of a magnetic recording medium (not shown) is introduced intothe MR element body 11 by a magnetic flux guide layer 14.

This magnetic flux guide layer 14 can be formed as a free layer andmagnetic flux guide layer or this magnetic flux guide layer can bebonded to the free layer.

In FIGS. 1 and 2, it is to be desired that the magnetic flux guidelayers 14 should be disposed behind the respective MR element bodies 11or the magnetic flux guide layers should be extended from the rearportions of the respective magneto-resistive effect element bodies.

A nonmagnetic insulating layer 15 made of Al₂O₃, for example, is buriedbetween the first and second electrode and magnetic shields 21 and 22.

First Embodiment

In this embodiment, the magneto-resistive effect element has a single SVtype GMR configuration. In this case, as FIG. 3 shows a schematiccross-sectional view thereof, its MR element body 11 has a laminationlayer structure comprising at least a free layer 1 the magnetization ofwhich is rotated in response to a detection magnetic field, a fixedlayer 2, an antiferromagnetic layer 3 for fixing a magnetization of thisfixed layer 2 and a spacer layer 4 interposed between the free layer 1and the fixed layer 2. In the illustrated example, thismagneto-resistive effect element has a configuration in which anunderlayer 5 is formed on the lower surface of the antiferromagneticlayer 3 and in which a magnetic flux guide layer 14, a magnetic gaplayer 6 and a capping layer 7 are formed on the free layer 1.

As shown in FIG. 1 or 2, this MR element body 11 is disposed between thefirst and second electrode and magnetic shields 21 and 22 in such amanner that the plane directions of the respective layers of the MRelement body 10 become parallel to these shields 21 and 22.

In this case, on a substrate 16 made of an AlTiC (AlTiC) layer having athickness of 100 μm, for example, there is formed the first electrodeand magnetic shield 21 made of an NiFe layer having thickness of 2 μm byplating, for example, on which the underlayer 5 shown in FIG. 3 isdeposited by sputtering. Subsequently, on this underlayer, there aredeposited the antiferromagnetic layer 3, the fixed layer 2, the spacerlayer 4 and the free layer 1 by sputtering, in that order, therebyresulting in a lamination layer film of the antiferromagnetic layer 3,the fixed layer 2, the spacer layer 4 and the free layer 1 being formed.Then, a first stripe portion is formed by patterning this laminationlayer film like a stripe extending along the track width direction, forexample.

An insulating layer 15 made of SiO₂ or Al₂O₃, for example, is formed soas to bury this first stripe portion, and a flat surface to which thefree layer 1 is faced is formed. An NiFe layer, for example, comprisingthe magnetic flux guide layer 14, for example, is formed on this flatsurface and a second stripe portion is formed like a stripe extending inthe thickness direction including this layer and the above-mentionedstripe portion below this layer, i.e., in the direction perpendicular tothe aforementioned stripe direction by patterning.

In this manner, the above-mentioned lamination layer film is left inonly the portion at which the first and second stripe portions crosseach other, whereby the MR element body 11 like a square one side ofwhich is 100 nm, for example, and which is based upon the laminationlayer structure portion of the antiferromagnetic layer 3, the fixedlayer 2, the spacer layer 4 and the free layer 1 is constructed.

Then, there is formed the stripe-like magnetic flux guide layer 14 underwhich there are laminated the insulating layer 15 made of SiO₂ or Al₂O₃,for example, the hard magnetic layer 12 and the similar insulating layer15 so as to bury the second stripe portion including the MR element body11 based upon the above-mentioned lamination layer structure portion,e.g., so as to be deposited on both side surfaces of the second stripeportion, for example. Then, the insulating layer 15 and the hardmagnetic layer 12 are selectively removed from the second stripe portionby a lift-off method, for example, whereby the surface can be made flat.As shown in FIG. 3, on this flat surface, there are formed the gap layer6 and the capping layer 7 on which there is further formed the secondelectrode and magnetic shield 22 formed of the NiFe plating layer havinga thickness of 2 μm, for example.

In the MR element body 11 formed between the first and second electrodeand magnetic shields 21 and 22 as described above, the thickness of thegap layer 7 shown in FIG. 3, for example, is selected in such a mannerthat the free layer 1 and the magnetic flux guide layer 14 may belocated at substantially the center between the first and secondelectrode and magnetic shields 21 and 22.

Then, the hard magnetic layers 12 are disposed at the positions opposingto respective side end portions of this free layer 1.

The free layer 1 and the fixed layer 2 can be each formed of a CoFe filmhaving a thickness of 5 nm, for example.

The free layer 1 is given a uniaxial anisotropy of an anisotropicmagnetic field of 5 [Oe] in the film plane direction shown by an arrow ain FIG. 1, for example, by film deposition in the magnetic fieldgenerated by a magnetic field of 500 [Oe], for example, and by vacuumannealing for 1 hour in the magnetic field generated by a magnetic fieldof 1000 [Oe] at 200° C.

The spacer layer 4 interposed between these free layer 1 and fixed layer2 can be formed of a conductive layer, for example, a Cu layer having athickness of 3 nm, for example.

Moreover, the antiferromagnetic layer 3 can be formed of a PtMn film,for example, having a thickness of 34.5 nm, for example.

The hard magnetic layers 12 are magnetized as shown by arrows b in onedirection which is the same direction as that of the anisotropicmagnetic field of the free layer as shown in FIGS. 1 and 2.

When the hard magnetic layers 12 are buried by the insulating layer 15and thereby electrically separated from the MR element body 11, they canbe each formed of a conductive CoCrPt film having a thickness of 40 nm,for example. The residual magnetization of the hard magnetic layers 12formed of the CoCrPt film is 670 [emu/cm³]. Moreover, when the hardmagnetic layers 12 are not electrically separated from the MR elementbody 11, these hard magnetic layers can be made of a Co—Fe₂O₃ filmhaving a high resistance.

The underlayer 5 and the capping layer 7 can be each formed of a Ta filmhaving a thickness of 3 nm, respectively.

The magnetic gap layer 6 can be formed of a nonmagnetic film, e.g., Cufilm having a thickness of 34.5 nm.

In this configuration, the magnetic flux guide layer 14 can also serveas the free layer 1 as well.

Then, the forward surface 13 can be formed by polishing and the MRelement body 11 can be directly faced to the forward surface, wherebythe magnetic flux guide layer 14 can be extended from themagneto-resistive effect element body to the rearward as shown inFIG. 1. Alternatively, as shown in FIG. 2, the front end of the magneticflux guide layer 14 may be faced to the forward surface 13 and the MRelement body 11 may be located at the position retreated from the frontend of the magnetic flux guide layer in the depth direction.

In the magnetic head 100 using this MR element 10, the forward surface13 comprises a surface by which the magnetic head 100 is brought incontact with a magnetic recording medium or the magnetic head is opposedto the magnetic recording medium.

In a flying type magnetic head, for example, this forward surface servesas a so-called ABS surface (Air Bearing Surface) by which the magnetichead can fly over a recording medium surface with a required spacebetween them due to an air flow generated by a relative movement of amagnetic recording medium, e.g., a magnetic disk and a magnetic head.

Then, according to the present invention, this configuration serves as aCPP type configuration in which a sense current is flowing between thefirst and second electrode and magnetic shields 21 and 22, i.e., the MRelement body 11 in the direction intersecting the film plane of thelamination layer film.

Further, the detection magnetic field may be introduced along the filmplane direction of the lamination layer film. At the same time, the biasmagnetic field HB generated by the hard magnetic layer 12 may be appliednot only in the direction intersecting substantially the direction inwhich the above-mentioned detection magnetic field is introduced butalso in the direction along the film plane, i.e., in the direction alongthe anisotropic magnetic field direction, shown by the arrow a, of thefree layer, e.g., in the direction shown by the arrow b.

Then, according to the present invention, in the above-mentionedconfiguration, for example, in particular, in the free layer, as will bedescribed later on in detail, under the condition that the detectionmagnetic field is not applied to the magneto-resistive effect element,magnetic fields which are substantially applied to the front end and therear end of the side into which the detection magnetic field isintroduced, to be concrete, magnetic fields determined by mainly theinduced magnetic fields generated by the above-mentioned sense current,i.e., magnetic fields determined by the current magnetic field HI andthe above-mentioned bias magnetic field HB are set to the samedirection.

Second Embodiment

In this embodiment, as FIGS. 5 and 6 show schematic longitudinalcross-sectional views of FIGS. 1 and 2, the magneto-resistive effectelement has a so-called dual SV type GMR element 10 in which MR elementbodies 11A and 11B having a pair of SV type GMR configurations aresymmetrically disposed across a common magnetic flux guide layer or afree layer and magnetic flux guide layer 14.

Particularly, in this case, as FIG. 4 shows a schematic cross-sectionalview of its MR element body 11, spacers 4A and 4B, fixed layers 2A and2B and antiferromagnetic layers 3A and 3B comprising the respectiveelement bodies 11A and 11B are disposed at both surfaces of the freelayer and magnetic flux guide layer 14 which serves also as the freelayers 1A and 1B as well.

In FIG. 4, elements and parts identical to those of FIG. 3 are denotedby identical reference numerals and therefore an overlapping explanationwill be omitted.

The free layer and magnetic flux guide layer 14, the spacer layers 4Aand 4B, the fixed layers 2A and 2B and the antiferromagnetic layers 3Aand 3B may have configurations similar to those of the free layer 1 orthe magnetic flux guide layer 14, the spacer layer 4, the fixed layer 2and the antiferromagnetic layer 3 in the aforementioned firstembodiment, for example.

Also in this embodiment, in the magnetic head 100 using this MR element10, its forward surface 13 comprises a surface by which the magnetichead comes in contact with and is opposed to a magnetic recordingmedium. In a flying type magnetic head, for example, this forwardsurface serves as what might be called an “ABS surface” (Air BearingSurface) by which the magnetic head can fly over a recording mediumsurface by a required space owing to an air flow produced when amagnetic recording medium, e.g., a magnetic disk and the magnetic headare moved in a relative relationship between them.

Further, also in this case, the magneto-resistive effect element has theCPP type configuration in which the sense current flows between thefirst and second electrode and magnetic shields 21 and 22, i.e., the MRelement body 11 in the direction crossing the film plane of itslamination layer film.

Furthermore, the detection magnetic field is introduced into thedirection extending along the film plane direction of the laminationlayer film. At the same time, the bias magnetic field HB caused by thehard magnetic layer 12 is applied to the direction crossing thedirection in which the above-mentioned detection magnetic field isintroduced and in the direction extending along the film plane, i.e., inthe direction extending along the anisotropic magnetic field directionshown by the arrow a in the free layer, e.g., one direction shown by thearrow b.

Then, according to the present invention, in such configuration, forexample, particularly in the free layer, under the condition that thedetection magnetic field is not applied to the magneto-resistive effectelement, as will be described later on, magnetic fields substantiallyapplied to this free layer at the front end and the rear end of the sideinto which this detection magnetic field is introduced, to be concrete,magnetic fields determined by mainly the induced magnetic fieldgenerated by the above-mentioned sense current, i.e., the currentmagnetic field HI and the above-mentioned bias magnetic field HB are setto the same direction, particularly, in the free layer.

Third Embodiment

In this embodiment, the magneto-resistive effect element has a TN typeMR configuration. In this embodiment, the magneto-resistive effectelement has a similar configuration to that of the first embodiment andis different only in that the spacer layer in the aforementioned firstembodiment is formed of an Al₂O₃ layer which is what might be called atunnel barrier layer formed by treating an Al layer having a thicknessof 0.6 nm by anodic oxidation.

Fourth Embodiment

In this embodiment, the magneto-resistive effect element has a TN typeMR configuration. In this embodiment, the magneto-resistive effectelement has a similar configuration to that of the above-mentionedsecond embodiment and is different only in that the spacer layer in theaforementioned second embodiment is formed of an Al₂O₃ layer which iswhat might be called a tunnel barrier layer formed by treating an Allayer having a thickness of 0.6 nm by anodic oxidation.

As mentioned before, according to the MR element 10 or the magnetic head100 of the present invention, in the free layer, under the conditionthat the detection magnetic field is not applied to themagneto-resistive effect element, as will be described later on indetail, magnetic fields substantially applied to the free layer at thefront end and the rear end of the side in which this detection magneticfield is introduced, to be concrete, magnetic fields determined bymainly the induced magnetic field generated by the above-mentioned sensecurrent, i.e., the current magnetic field HI and the above-mentionedbias magnetic field HB are set to the same direction, particularly, inthe free layer. This will be described.

FIG. 7 shows the bias magnetic field direction HB of the bias magneticfield applied to the free layer 1 and a current magnetic field (shown byan arrow c) within the film plane as is obtained by a numericalcalculation based upon a finite element method. FIG. 7 shows the statein which the sense current Is flows to the upper direction perpendicularto the sheet of the drawing.

In the present invention, at respective central portions of a front end1F and a rear end 1R of this free layer 1, the directions of themagnetic fields applied to this free layer 1 are set to the directionextending along the anisotropic magnetic field of the free layer 1 andthe same direction.

This will be described.

When a magnetic field component Hx in a direction x perpendicular to anexternal magnetic field Hsig of the current magnetic field HI on acenter line parallel to the external magnetic field (detection magneticfield) Hsig of the free layer is calculated from the Bio-Savart Law andthe following equation (1) obtained from a coordinate system defined asshown in FIG. 8, this component is calculated as shown by a dashed linein FIG. 9A. In this case, in the magnetic field component Hx, a polarityof the same direction as that of the bias magnetic field HB is set to apositive polarity.

$\begin{matrix}{{H_{x}( {x,y,{z = 0}} )} = {\frac{I_{s}}{10}{\int_{x^{\prime} = 0}^{x^{\prime} = L}{\int_{y^{\prime} = 0}^{y^{\prime} = L}{\int_{z^{\prime} = h}^{z^{\prime} = h}{\frac{y^{\prime} - y}{( {z^{\prime 2} - R^{2}} )^{3/2}}{\mathbb{d}z^{\prime}}{\mathbb{d}y^{\prime}}{\mathbb{d}x^{\prime}}}}}}}} & ( {{Equation}\mspace{11mu} 1} )\end{matrix}$whereinR=√{square root over ((x−x′)²+(y−y′)²)}{square root over((x−x′)²+(y−y′)²)}

H_(x): x component(Oe) of current magnetic field

x,y,z : position in the device (cm)

I_(s): sense current (A)

In this case, since the current magnetic field component Hx in the tip,i.e., the front end 1F is −120 [Oe] and becomes larger than the magneticanisotropic magnetic field, it is to be understood that the free layer 1cannot be nucleated as a single magnetic domain without application ofthe bias magnetic field HB. Then, in this case, at the lowest, there isrequired the intensity of the bias magnetic field such that thedirection of the synthesized magnetic field of the current magneticfield component Hx and the bias magnetic field HB become the samedirection at the center line A in which the magnetic field component Hxbecomes largest.

Therefore, characteristics of the material and the film thickness of thehard magnetic layer 12 are adjusted in such a manner that the biasmagnetic field applied onto the center line A may exceed 120 [Oe], e.g.,may reach 130 [Oe]. As a consequence, the synthesized magnetic field onthe center line A is obtained as shown by a solid curved line in FIG.9A.

With this configuration, the synthesized magnetic field of the currentmagnetic field HI and the bias magnetic field HB are oriented in thesame direction in the direction crossing, e.g., perpendicular to thedirection of the external magnetic field (detection magnetic field) Hsignot only on the center line A but also in the whole region of the freelayer 1 with the result that the free layer 1 can be nucleated as asingle magnetic domain in its whole region.

However, at that time, a synthesized magnetic field as large as 270 [Oe]is applied to the rear end 1R of the free layer 1. Hence, it is to beconsidered that a sensitivity is lowered at the rear end of the freelayer 1.

However, in the above-mentioned configuration of the present invention,since the magneto-resistive effect element has the configuration inwhich the MR element 10 is sandwiched between the first and the secondmagnetic shields 21 and 22, i.e., the so-called shield typeconfiguration, a region in which the detection magnetic field isintroduced i.e., a detection space is limited so that a resolution ofthe magneto-resistive effect element can be increased. According to theshield type configuration, when magnetic flux of the detection magneticfield is propagated from the front end (tip) of the free layer to therear end, it is customary that a magnetic field is attenuated due to theleakage of magnetic flux leaked to the shields 21 and 22 adjacent to themagneto-resistive effect element body.

It is well known that a degree to which this magnetic field isattenuated by the leakage of the magnetic flux can be expressed as inthe following equation (3) by using a magnetic flux penetrationcharacteristic length λ defined in the following equation (2).

$\begin{matrix}{\lambda = \sqrt{\frac{\mu\;{gt}}{2}}} & ( {{Equation}\mspace{11mu} 2} )\end{matrix}$

-   -   μ: magnetic permeability of the free layer    -   g: distance from the free layer to the shield    -   t: layer thickness of the free layer

$\begin{matrix}{{\Phi(y)} = {{\Phi(0)}\frac{\sinh( {( {D - y} )/\lambda} )}{\sinh( {D/\lambda} )}}} & ( {{Equation}\mspace{11mu} 3} )\end{matrix}$

-   -   Φ(y): magnetic flux at the distance y from the top end of the        free layer, i.e., the magnetic flux guide    -   D: distance from the front end to the rear end of free layer,        i.e., the magnetic flux guide    -   λ: flux penetration characteristic length shown by the equation        2.

In the above-mentioned configuration of the present invention, theattenuation degree of the magnetic field is calculated as shown in FIG.9C. From FIG. 9C, it is to be understood that the magnetic flux isthoroughly attenuated at the rear end portion of the free layer 1. Thatis, it is to be understood that the contribution of the attenuation ofthe magnetic flux to the magnetic resistance change in the rear endportion 1R is extremely small compared with the front end 1F. Therefore,as mentioned before, even when the magnetic field of the x directioncomponent is remarkably increased at the rear end portion of the freelayer 1, it is possible to avoid a trouble caused by such increasedmagnetic field.

On the other hand, if the sense current flows in the direction oppositeto the direction in which the sense current Is flows as shown in FIG. 7,then when the similar component Hx in the direction x perpendicular tothe external magnetic field Hsig at the center line A is calculated,such component is calculated as shown by a dashed line in FIG. 9B.Further, when a bias magnetic field necessary for nucleating the freelayer 1 as the single magnetic domain is applied to the free layer, theabove component is calculated as shown by a solid line in FIG. 9B.

Then, in this case, although a sensitivity can be increased near therear end portion 1R of the free layer 1, a benefit of such increasedsensitivity can hardly be obtained due to the above-mentioned magneticflux attenuation effect.

That is, according to the present invention, by selecting a relationshipbetween the direction and intensity of the bias magnetic field HB and arelationship between the conducting direction and conducting currentamount of the sense current, i.e., the direction and intensity of thecurrent magnetic field HI, the change of the magnetic field of thedetection magnetic field Hsig can be detected more efficiently, i.e., ahigh reproduced output can be realized.

This will further be described with reference to FIG. 10. In this sheetof drawing, there are illustrated magnetic field distributions obtainedin a dual type MR element in which a pair of MR element bodies 11A and11B are disposed across the free layer 1 and magnetic flux guide layer14. In FIG. 10, a curve 31 shows a magnetic field distribution of thecurrent magnetic field HI obtained under the condition that only thesense current flows to the free layer, i.e., under the condition thatthe bias magnetic field is not applied to the free layer. A curve 32shows a magnetic field distribution obtained when the bias magneticfield HB of the same direction as that of the magnetic field HI in thefront end 1F of the free layer 1 is applied to this current magneticfield HI. Although magnetic fields HF and HR of total sums (hereinafterreferred to as “total sum magnetic fields”) of the current magneticfields HI and the bias magnetic fields HB of the front end side and therear end side are set to the same direction, the intensities of thesecurrent magnetic fields are assumed to be |HF|>|HR|.

A curve 33 shows a magnetic field distribution obtained when the biasmagnetic field HB in the opposite direction to that of the curve 32 and|HF|<|HR| is satisfied although the magnetic field HR on the rear endside and the magnetic field HF on the rear end side are set to the samedirection.

As mentioned before, in order to increase the sensitivity of theelement, the state of the curve 33 in which |HF|<|HR| is satisfiedshould be preferable. However, in the case of the magneto-resistiveeffect element including the magnetic flux guide layer 14 shown in FIG.10, the current magnetic field HI and the bias magnetic field HB appliedto the magnetic flux guide layer 14 affect the reproduced output of theelement. That is, in the state shown by the curve 33,

|HF| is small so that the sensitivity can be increased at the front endin which the magnetic flux efficiency is high. However, since |HR| islarge, a magnetic flux extracting effect at the portions behind theelement bodies 11A and 11B of the magnetic flux guide layer 14 becomessmall so that magnetic flux directly leaked from the element bodies 11Aand 11B to the magnetic shields is increased unavoidably.

On the other hand, in the state shown by the curve 32, since |HF| islarge, although the sensitivity is lowered at the front end in which themagnetic flux efficiency is high, |HR| is small with the result that themagnetic flux extracting effect at the portions behind the elementbodies 11A and 11B of the magnetic flux guide layer 14 is increased.Thus, it is possible to decrease the magnetic flux directly leaked fromthe element bodies 11A and 11B to the magnetic shields.

That is, we cannot always say which reproduced output is higher inintensity between the state shown by the curve 33 in which thesensitivity of the element is small but the magnetic flux leakage islarge and the state shown by the curve 32 in which the sensitivity ofthe element is small but the magnetic flux leakage is small, and thereproduced output is changed depending upon the structure and dimensionof the element. Accordingly, which configuration to select should bedetermined in accordance with the structure and dimension of theelement.

Further, when a difference between the reproduced output in the stateshown by the curve 32 and in the state shown by the curve 33 is not solarge, it should be preferable to select the configuration which canpresent the state of the curve 32 in which the sum of the currentmagnetic field HI and the bias magnetic field HB is large at the frontend in which the contribution to the reproduced output is large and thestability is excellent.

That is, according to the configuration of the present invention, sincethe total magnetic fields are set to the same direction over the wholeregion of the front and the rear of the free layer 1, the free layer isnucleated as a single magnetic domain over the whole region, therebyimproving the Barkhausen noise effectively. In addition, by increasingthe magnitude of the total magnetic field at the front end or the rearend of the free layer, there can be achieved the effect that thesensitivity can be increased much more or the stability can be improved.

Further, while the magnetic head 100 according to the present inventioncan be used as a head for detecting a signal from a magnetic recordingmedium, i.e., a reproducing head, when the magnetic head according tothe present invention comprises a recording and reproducing head, aninduction type thin-film recording head is disposed on the secondmagnetic shield and electrode 22, for example, shown in FIG. 1 or 2, forexample, and thereby can be integrally formed with the above recordinghead as one body.

FIG. 11 shows a schematic perspective view of such example. In thisexample, the magnetic head according to the present invention can beconstructed as a magnetic recording and reproducing head by laminatingan electromagnetic induction type thin-film magnetic recording head 130,for example, on the inventive magnetic head 100 using the MR elementaccording to the present invention as a magnetic sensing portion.

Then, at the portion which faces the forward surface 13, there is formeda nonmagnetic layer 131 made of an SiO₂ layer and the like, for example,comprising the magnetic gap of the recording head 130.

Then, a coil 132, which is formed by patterning a conductive layer, forexample, is formed on the rear portion. An insulating layer is depositedon the coil 132, and a through-hole 133 is bored through the insulatinglayer and the nonmagnetic layer 131 at its central portion of this coil132 to thereby expose the second shield and electrode 2.

On the other hand, the front end of the forward surface 3 is opposed tothe nonmagnetic layer 131 and, on the nonmagnetic layer 131, there isformed a magnetic core layer 134 which is brought in contact with thesecond shield and electrode layer 22 exposed through the through-hole133 across the portion in which the coil 132 is formed.

In this manner, there is constructed the electromagnetic induction typethin-film recording head 130 in which a magnetic gap g prescribed by thethickness of the nonmagnetic layer 131 is formed between the front endof the magnetic core layer 134 and the second shield and electrode layer2.

On this magnetic head 130, there is formed a protecting layer 135comprised of an insulating layer as shown by a dot-and-dash line.

As described above, there can be constructed the recording andreproducing magnetic head 130 in which the magneto-resistive effect typereproducing magnetic head 100 according to the present invention and thethin-film type recording head 130 are laminated and thereby integratedas one body.

The present invention is not limited to the above-mentioned examples andcan be modified as various types of magneto-resistive effect elementssuch as a so-called synthetic type, a single or dual type in which afixed layer, for example, is formed as a lamination layerferri-structure. Further, materials and thicknesses of respective layersare not limited to the above-mentioned examples and can be variouslymodified.

As described above, according to the configuration of the presentinvention, the magneto-resistive effect element has the magnetic shieldtype configuration in which the magneto-resistive effect element isdisposed between the first and second magnetic shields and has also theCPP type configuration. Under the condition that the detection magneticfield is not applied to this configuration, since the directions of themagnetic fields substantially applied to the free layer, i.e., thedirections of the total magnetic fields are set to the same direction atthe front end and the rear end, in actual practice, over the front endand the rear end, the free layer can be nucleated as the single magneticdomain over the whole region of the side end portion of the free layer.As a result, the Barkhausen noise can be improved effectively.

Further, since the respective total magnetic fields |HF| and |HR| areselected so as to satisfy |HF|<|HR| or |HF|>|HR|, the stability orsensitivity of the magneto-resistive effect element can be improved muchmore. Therefore, there can be constructed the magneto-resistive effectelement which is excellent in reproducibility and the magnetic headwhich uses this magneto-resistive effect element as the magnetic sensingportion.

LIST OF REFERENCE NUMERALS AND ITEMS Reference Numerals Items  1 thefree layer  1F the front end  1R the rear end  2, 2A, 2B the fixedlayers  3, 3A, 3B the antiferromagnetic layers  4, 4A, 4B the spacerlayers  5 the underlayer  6 the magnetic gap layer  7 the capping layer 10 the MR element  11 the MR element body  12 the hard magnetic layer 13 the forward surface  14 the magnetic flux guide layer  15 theinsulating layer  16 the substrate 100 the MR type magnetic head 130 themagnetic induction type thin-film magnetic head 131 the nonmagneticlayer 132 the coil 133 the through-hole 134 the magnetic core layer 135the protecting layer

1. A magneto-resistive effect element comprising: a magneto-resistiveeffect element body and a hard magnetic layer for applying a biasmagnetic field to said magneto-resistive effect element body disposedbetween opposing first and second magnetic shields, each of the magneticshields made of a soft magnetic material; the magneto-resistive effectelement body having a lamination layer film oriented in a film planedirection parallel with said first and second magnetic shields, thelamination layer film comprising: a free layer the magnetization ofwhich is rotated in response to an external magnetic field; a fixedlayer; an antiferromagnetic layer; and a spacer layer interposed betweensaid free layer and said fixed layer; the hard magnetic layer beingformed in two portions disposed at positions opposite respective sideend portions of said free layer; the magnet-resistive effect elementconfigured such that a sense current flows to said magneto-resistiveeffect element body in the direction intersecting the film planedirection of said lamination layer film and a detection magnetic fieldis introduced in the direction extending along the film plane directionof said lamination layer film, said bias magnetic field is applied insubstantially the direction intersecting the direction in which saiddetection magnetic field is introduced and in the direction extendingalong said film plane direction and directions of magnetic fieldssubstantially applied to the front end and the rear end of the side intowhich said detection magnetic field is introduced are set to the samedirection in said free layer under the condition that said detectionmagnetic field is not applied to said magneto-resistive effect element.2. A magneto-resistive effect element according to claim 1,characterized in that said magnetic fields substantially applied to thefront end and the rear end of the side into which said detectionmagnetic field is introduced in said free layer under the condition thatsaid detection magnetic field is not applied to said magneto-resistiveeffect element are increased in said rear end side.
 3. Amagneto-resistive effect element according to claim 1, characterized inthat said magnetic fields substantially applied to the front end and therear end of the side in which said detection magnetic field isintroduced in said free layer under the condition that said detectionmagnetic field is not applied are increased in said front end side.
 4. Amagneto-resistive effect element according to claim 1, 2 or 3,characterized in that said magneto-resistive effect element body has aspin-valve type configuration in which said spacer layer is comprised ofa nonmagnetic conductive layer.
 5. A magneto-resistive effect elementaccording to claim 1, 2 or 3, characterized in that saidmagneto-resistive effect element body has a tunnel type configuration inwhich said spacer layer is comprised of a tunnel barrier layer.
 6. Amagnetic head using magneto-resistive head characterized in that amagnetic sensing portion of the magnetic head is comprised of amagneto-resistive effect element, said magneto-resistive effect elementcomprising: a magneto-resistive effect element body and a hard magneticlayer for applying a bias magnetic field to said magneto-resistiveeffect element body disposed between opposing first and second magneticshields, each of the magnetic shields made of a soft magnetic material;the magneto-resistive effect element body having a lamination layer filmoriented in a film plane direction parallel with said first and secondmagnetic shields, the lamination layer film comprising: a free layer themagnetization of which is rotated in response to an external magneticfield; a fixed layer; an antiferromagnetic layer; and a spacer layerinterposed between said free layer and said fixed layer; the hardmagnetic layer being formed in two portions disposed at positionsopposite respective side end portions of said free layer; themagnet-resistive effect element configured such that a sense currentflows to said magneto-resistive effect element body in the directionintersecting the film plane direction of said lamination layer film anda detection magnetic field is introduced in the direction extendingalong the film plane direction of said lamination layer film, said biasmagnetic field is applied in substantially the direction intersectingthe direction in which said detection magnetic field is introduced andin the direction extending along said film plane direction anddirections of magnetic fields substantially applied to the front end andthe rear end of the side into which said detection magnetic field isintroduced are set to the same direction in said free layer under thecondition that said detection magnetic field is not applied to saidmagneto-resistive effect element.
 7. A magnetic head usingmagneto-resistive head according to claim 6, characterized in that saidmagnetic fields substantially applied to the front end and the rear endof the side into which said detection magnetic field is introduced underthe condition that said detection magnetic field is not applied to saidmagneto-resistive effect element are increased in intensity in said rearend side of said free layer.
 8. A magnetic head using magneto-resistivehead according to claim 6, characterized in that said magnetic fieldssubstantially applied to the front end and the rear end of the side intowhich said detection magnetic field is introduced under the conditionthat said detection magnetic field is not applied to saidmagneto-resistive effect element are increased in intensity in saidfront end side of said free layer.
 9. A magnetic head usingmagneto-resistive head according to claim 6, 7 or 8, characterized inthat said magneto-resistive effect element body has a spin-valve typeconfiguration in which said spacer layer is comprised of a nonmagneticconductive layer.
 10. A magnetic head using magneto-resistive headaccording to claim 6, 7 or 8, characterized in that saidmagneto-resistive effect element body has a tunnel type configuration inwhich said spacer layer is comprised of a tunnel barrier layer.